The Pokémon Adventure Series is a collection of picture books released by Golden Books. Each book is an adaptation of an anime episode. There are four books in total. All four books in the Pokémon Adventure Series were written by Diane Muldrow and illustrated by DRI Artworks.

The group decides to rent a hot air balloon to get close to the Butterfree like the other Butterfree Trainers are doing. At Brock's suggestion, Ash throws his own Butterfree's Poké Ball into the air, releasing it and coaxing it to go out there and find its mate. Butterfree finds and flies over to a pink one still by itself, but despite his fluttering around it, the pink one wants nothing to do with Ash's Butterfree. Ash calls for Butterfree to have confidence in itself, and commands it to show the pink one its Whirlwind attack. This fails to impress the pink Butterfree.

The group notices a helicopter with a red R speed toward the Butterfree swarm. Ash realizes the helicopter belongs to Team Rocket, and a giant net comes out of the bottom of the helicopter and begins to scoop up hundreds of Butterfree. Ash's Butterfree flies to the net, and finds that the pink Butterfree had been caught. Ash's Butterfree tackles the chopper, but the attack and its second attempt, a Stun Spore attack, are ineffective. The helicopter proceeds to get away, but Ash's Butterfree follows them, and eventually Ash and his friends find Butterfree waiting for them. Ash's Butterfree leads them to a warehouse in a canyon where Team Rocket hid the stolen Butterfree.

Team Rocket examines their catch, but hears the sound of glass breaking and, after asking who there was, find that Ash and his friends have broke through the window. The group mimics Team Rocket's motto, and Ash sends out Butterfree and Misty her Starmie. Watched hopefully by the pink Butterfree, Ash's Butterfree attacks the net multiple times before, on the final try, tearing a hole through it and freeing the Butterfree. Jessie swings at Starmie, stunning it, but Misty revives Starmie with water, making it capable of battling again. Brock opens the door of the warehouse, and the Butterfree escape. Team Rocket gets back into their helicopter, and catches up with the Butterfree swarm with Ash and his friends, in the hot-air balloon, following them.

Pikachu hops on Butterfree's back, together flying over to Team Rocket's helicopter. Pikachu lands on the chopper and uses ThunderShock, causing Team Rocket to blast off. The pink Butterfree now flutters in the air for Ash's Butterfree, and Ash, feeling sad and knowing that it is time for Butterfree to leave him and fly across the ocean with the pink Butterfree, kneels down to talk to his also sad Butterfree. Ash assures Butterfree not to worry, telling his Butterfree that he will tell his other Pokémon that it is on a trip and that it will come back someday, before saying good-bye. The two Butterfree then take off together into the sky, Ash thinking about all the good times he had with Butterfree, waving and calling that he will always remember Butterfree, thanking it for everything. Brock comforts Ash, saying that he raised Butterfree to have a lot of courage, and that he thinks Ash just proved that he has lots of courage too.

Errors

On one page, Butterfree does not wear a scarf. On the second, it does, with no explanation provided.

The text of the book says Team Rocket's helicopter had a red "R" on the door. However, the "R" was actually on the front of the helicopter.

Attack of the Prehistoric Pokémon

Attack of the Prehistoric Pokémon is the second book in the Pokémon Adventure Series. This book is based on the events of the anime episode of the same name.

In the story, Ash, Misty, and Brock travel to Grampa Canyon and discover that a Fossil dig is underway. The friends decide to participate in hopes of finding a rare Pokémon Fossil.

Meanwhile, Team Rocket prepares to detonate some dynamite in an attempt to create a distraction and take all of the Fossils for themselves. Unluckily for them, however, Ash and his friends overhear their plans, and they decide to attempt to stop them from blowing up the canyon.

Inside the cavern, Ash and company discover four ancient Pokémon: Omanyte, Omastar, Kabuto, and Kabutops. Jessie theorizes that the explosion woke them up from a long hibernation. Before the creatures attack, however, they mysteriously run away.

In the meantime, Misty, Brock, and Squirtle are frantically searching for their lost friends. Suddenly, a pile of rocks bursts open, breaking a wild Aerodactyl free. The Aerodactyl has Ash in its grip, with Pikachu and Ash's Charmeleon hanging on to its tail. Ash's Charmeleon evolves into a Charizard so that it can chase Aerodactyl through the air. Charizard uses its Flamethrower attack on Aerodactyl, narrowly missing both it and Ash.

Misty encounters Jigglypuff and gets it to use its Sing ability. Jigglypuff sings its soothing lullaby, causing Aerodactyl to fall asleep, dropping Ash back on the ground.

Once the commotion is over, the Fossil dig resumes and Ash and friends leave the canyon with a mysterious Pokémon Egg. The story ends with the friends wondering what kind of Pokémon could be inside this Egg.

In the story, Ash, Misty, and Brock finally arrive in Vermilion City and are overjoyed to have found civilization after 2 weeks. Pikachu then collapses from hunger, so they decide that getting a bite to eat should be their first priority, so they head to the Pokémon Center.

As soon as they arrive to the Pokémon Center, a Rattata is wheeled in on a stretcher and Nurse Joy exclaims that it is the fifteenth Pokémon to be brought in that was defeated by Lt. Surge. Seeing the Rattata in the condition it was in made Pikachu nervous about Ash's upcoming battle with Lt. Surge. However, Ash was confident and tried to reassure Pikachu.

After a meal and some rest, Ash, Misty, and Brock headed to the Vermilion Gym for Ash's battle. A man called out for Lt. Surge, who then came into the room, towering over Ash. Lt. Surge then noticed Ash's Pikachu and made fun of them for being smaller than he was. This made Ash angry, so Lt. Surge sent out his Pokémon. A large Raichu emerged from the ball and glared down at Pikachu. Ash then scanned Raichu with his Pokédex, and while he was nervous of his opponent, tried to stay positive. Lt. Surge continues mocking Ash, telling him to evolve his Pokémon as soon as he catches them. Ash said otherwise, explaining that there's more to raising a Pokémon than evolution, but Lt. Surge argued that Pokémon perform their best when they know lots of powerful attacks.

Unable to come to a consensus, Ash and Lt. Surge start the battle. Raichu hit Pikachu with a powerful ThunderShock, and brought him to the brink of defeat. However, Pikachu refused to give up until he had defeated Raichu. But Raichu still overpowered him, and Pikachu was unable to do much. At the window, Team Rocket was spectating Ash's battle, and upon seeing Pikachu being beaten, questioned its true value.

Pikachu was then rushed to the Pokémon Center and nursed back to health. Nurse Joy walks into the room and gives Ash a Thunderstone, thinking it might aide Pikachu in defeating Raichu. Misty reminds Ash that Pikachu won't be able to revert to a Pikachu once it has become a Raichu, so Ash decided that Pikachu should be the one to decide.

Still watching Ash, Jessie remarks that Ash was letting Pikachu choose whether to evolve or not. As Pikachu slaps the stone from Ash's hand, Team Rocket sobs at how brave Pikachu is, how he will battle and defeat Raichu to prove that a Pikachu can be just as powerful.

Ash then promised to Pikachu that together, they would defeat Pikachu. After a long rest, they return to the Gym for a rematch. Lt. Surge eagerly calls out his Raichu and the battle commences. This time, Ash took advantage of Pikachu's speed, which Raichu lacked. Lt. Surge then ordered Raichu to shut Pikachu down with a Thundershock, but Pikachu dodged by standing on his tail. Raichu had then run out of electricity and left itself defenseless. Pikachu then landed a final blow, knocking Raichu out.

Lt. Surge happily handed the Thunder Badge to Ash, proud to have had such an inspiring battle. Ash then picked up Pikachu and the two shared a victorious laugh, and Team Rocket decided that Pikachu was still worth stealing.

Errors

During Raichu and Pikachu's first battle, the book claims that "Raichu easily overpowered Pikachu with thunder punches and thunder kicks." However no such move exists.